1. Field of the Invention
This invention relates to novel carbostyril derivatives and a process for preparing the same. More particularly, this invention relates to novel 5-[1-hydroxy-2-(substituted-amino)]-ethyl-8-hydroxy-3,4-dihydrocarbostyril derivatives and a process for preparing the same.
2. Description of the Prior Art
It is well known that certain carbostyril derivatives exhibit useful pharmaceutical activities. Representative compounds of this type have been disclosed in Journal of Medical Chemistry, Vol. 15, No. 3, pp. 260-266 (1972), Japanese Patent Publication No. 38789/1971 and Chemical Abstracts, 62, 16212e (1965), etc. However, these prior art references do not teach that the compounds having a (1-hydroxy-2-substituted-amino)ethyl group at the 5-position of the carbostyril moiety possess an excellent .beta.-adreno-receptor stimulating activity.
It has been found that 8-hydroxy-3,4-dihydrocarbostyril derivatives having a (1-hydroxy-2-substituted-amino)ethyl group at the 5-position of the carbostyril moiety and pharmaceutically acceptable acid addition salts thereof possess a .beta.-adreno-receptor stimulating activity, and therefore, are useful as a therapeutic agent such as bronchodilator, a peripheral vasodilator and an antihypertensive agent, particularly for treating bronchial asthma.